If you really like Jennifer Lopez and Matthew McConaughey, don't encourage movies like this.

The Wedding Planner begins with footage of a seven-year-old girl performing a wedding ceremony with her Barbies -- a fitting opening, since the movie that ensues could almost be the result of a screenwriter transcribing the play scenario enacted by a small child and her dolls. If you were (or are) a child very much like this little girl, you're in the perfect target demographic for the movie. If you're the boyfriend of such a person, your woman is going to owe you big time after she drags you to this. Think My Best Friend's Wedding, subtract gay best friend, dorky karaoke scene, charm, and any hint of malice or conflict, and you've got it.

Jennifer Lopez is Mary (as in "The Virgin . . ."), an obsessive San Francisco wedding planner who treats nuptial ceremonies like military operations, delivering preplanned "from the heart" speeches to nervous brides, using military-style jargon ("F.O.B." is father of the bride, "Dark Tower" a hairdo tall enough to block the video cameras), barking orders into a headset, and even feeding the best man his "spontaneous" toast via a hidden earpiece. The alleged irony of the film is that, while planning the happiness of couples everywhere, Mary hasn't had any kind of love life herself ("Those who can't wed, plan"). That a woman as rich and as beautiful as she is has no dating prospects is something you just have to accept, but perhaps the tight bun her hair is often tied in makes her look too uptight. That, or the fact that her main hobby is playing Scrabble.

Mary's dating prospects are so bad that her Italian father (Alex Rocco) has taken the time to try to arrange her marriage to a childhood acquaintance named Massimo (Justin Chambers), a former mud-eating nerd who now rides a motor scooter, obsesses over his machismo, drinks wine from the bottle, and tells Mary how ugly she used to be. He is good-looking, but that's not enough. Despite her father's insistence that real love doesn't just come out of the blue, she holds out hope, and this being a movie, she is ultimately proved correct.

One high-heeled shoe caught in a manhole as a stereotypical Asian bad driver knocks a huge dumpster directly at Mary later, she is literally swept off her feet by Dr. Steve Edison (Matthew McConaughey), a charming pediatrician with a slow Southern drawl and laid-back sense of humor. He's the perfect guy, sensitive and masculine. He even has an annoyingly cutesy quirk: buying M&Ms and throwing away all the nonbrown ones because they have artificial colors, and the brown ones are the color of chocolate (hasn't anyone told him that the coloring is actually on the candy shell, which isn't naturally brown . . . ah, never mind). So anyway, Steve and Mary go out to a movie and dance in Golden Gate Park and have a great time, only the next day she finds out he's engaged. To her newest, richest client, Fran (Bridgette Wilson-Sampras, of Mortal Kombat). Ain't that a kick in the pants?

Perhaps one would expect a little comic mayhem to ensue. But one would be wrong. Mary befriends Fran and decides to be professional about the whole thing. Dorky Massimo shows up periodically to try to add humor, then abruptly transitions from reckless jerk to caring empath. Kevin Pollak appears for a minute or two as Steve's best friend, never to be seen again. And, this being San Francisco, we couldn't have a complete movie without at least one prissy gay guy, in this case a dance instructor played by Fred Willard.

Like Save the Last Dance, The Wedding Planner is written and directed by first-timers (director Adam Shankman is a dance choreographer; former husband-and-wife writing team of Pamela Falk and Michael Ellis claim this as their only produced screenplay), and it shows: The film is laden with contrivances. To cite a few examples among many: Why, when being questioned about her new dream guy (Steve) by Fran, does Mary tell her absolutely everything about him except his name, which would eliminate all confusion right away by inadvertently revealing him as Fran's fiancé? Why doesn't Mary speak up when Massimo publicly claims to be engaged to her, thereby saving herself a sizable amount of embarrassment? Why does Massimo suddenly undergo a complete personality change, and why does a hardened and cynical single like Mary instantly believe it? The answer to all of these questions, of course, is that there'd be no movie if these people acted like real people. And while romantic fantasy is frequently unrealistic, it is the duty of the filmmakers to persuade us to believe it -- an effect not achieved by making things up as you go along, as these folks seem to have done.

Even bigger than any of the plot mysteries, however, is why McConaughey and Lopez would be attracted to the script in any way. McConaughey's taken his fair share of knocks in the press for the undeserved hype surrounding his breakthrough in A Time to Kill, but the man is nothing if not natural on camera, and he's about the only thing that saves The Wedding Planner from being instantly forgettable. It takes a good deal of charm to make lines like "What if something I think is great is great, but it's not as great . . . as something greater?" sound plausible, but one can almost believe it comes from his heart as delivered herein. As for Lopez, she undoubtedly wants to craft a fully developed leading-lady persona after her butt-kicking roles in the likes of The Cell and Out of Sight, but she's not helping herself by choosing bad scripts like this one or by singing a horrible pop song for the soundtrack, which also includes the syrupy likes of Olivia Newton-John, John Denver, and Sourceror. It's enough to make you wish Lopez's real-life beau, Puff Daddy, would show up and commence the busting off of caps in asses.